At age 14, he became the youngest player ever invited to the MLB European Academy in Tirennia, Italy. In the 2009 World Youth Championship, Lars was 1-1 with a 5.00 ERA and struck out a team-high nine batters in his nine innings of work. He beat the Czech Republic but lost to Cuba. Huijer was part of the Dutch Junior National Team that played at the 2010 World Junior Championship in Canada. He beat Panama in a relief outing and got no-decisions in a rocky start against the Czech Republic and a strong game against Italy.

His debut was in Hoofdklasse in 2010; in one game, he struck out 3 in 2 2/3 shutout innings. In 2011, he was a starting pitcher for the Hoofddorp Pioniers, where he started with a 2-2 record in seven starts with an ERA of 5.67. He has struck out 14 batters in 33 1/3 innings, walking twelve.